Waterfall and Spiral ModelProject Management
Reported by: Honey Mae Llanto
Waterfall Model
It is a model which was developed for software development; that is to create software. This was first put forth by Winston Royce in 1970 in one of his articles.
Waterfall Model Phases
Analysis Design Technical Design/ Detailed Design Implementation and Coding Testing Integration Acceptance Test Management and Maintenance
Benefits of Waterfall Model
The project requires the fulfillment of one phase, before proceeding to the next.
Provides structure to inexperienced staff
Works well when quality is more important than cost or schedule
Shortcomings of Waterfall Model
Many software projects are dependent upon external factors.
A huge amount of time is also wasted. Little opportunity for customer to
preview the system. All requirements must be known
upfront
When to use the Waterfall Model
Requirements are very well known Product definition is stable Technology is understood New version of an existing product
Spiral Model
This model is preferred for large, expensive and complicated projects. It combines the features of Prototyping and Waterfall models.
Spiral Model Phases
Envisioning Phase Planning Phase Developing Phase Stabilizing Phase Deploying Phase
Spiral Model Strengths
Early and frequent feedback from users
Users see the system early because of rapid prototyping tools
Provides early indication of risks. Users can be closely tied to all
lifecycle steps
Spiral Model Weaknesses
Time spent for evaluating risks too large
The model is complex Risk assessment expertise is
required May be hard to define objective,
verifiable milestones that indicate readiness to proceed through the next iteration
When to use Spiral Model
When creation of a prototype is appropriate
Requirements are complex Significant changes are expected Users are unsure of their needs
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